A. Yu. Grinev - Dr.Sc. (Eng.), Professor, Department of Radiophysics, Antennas and Microwave Technics, Moscow Aviation Institute (National Research University). E-mail: grinevau@yandex.ru A. P. Volkov - Post-graduate Student, Department of Radiophysics, Antennas and Microwave Technics, Moscow Aviation Institute (National Research University); engineer, JSC «Radio Engineering Corporation «Vega» (Moscow). E-mail: tkoh@yandex.ru G. F. Moseichuk - Head of Laboratory, JSC «V.Tikhomirov Scientific Research Institute of Instrument Design» (Zhukovsky). E-mail: niki@nio11.niip.ru A. I. Sinani - Ph.D. (Eng.), Chief Designer, Deputy General Director on Science Research, JSC «V.Tikhomirov Scientific Research In-stitute of Instrument Design» (Zhukovsky)

Radar visibility is determined by strongly reflecting components: an air inlet, a hull, wings etc. The antennas and antenna arrays are such components. The back-scattering pattern (BSP) is a function of the monostatic scattering performance (radar transmitter and receiver co-locate) versus angular coordinates. For the analysis of the scattering field-s structure the following modes are emphasized: antenna resonant mode scattering, antenna terminal mode scattering, structural mode scattering. Antenna resonant mode scattering is directly a function of the currents on the antenna. The scattering from the antenna resonant mode is proportional to the gain and antenna pattern of the antenna. Antenna terminal mode scattering is a function of how the antenna is terminated or loaded. Structural mode scattering is caused by discontinuities, impedance mismatch, material boundaries. Out of operating band the scattering field is defined by the structural mode. BSP features for L-band antenna array are caused by lobes of scattering with maximal strength in backward direction (Bragg lobes). Bragg scattering specifics has been studied using L-band in-line array antenna model. Results of the back-scattering pattern (BSP) numerical calculation are presented for in-line L-band active electrically steerable array for the case of X-band sounding. The antenna system is arranged inside of controlled slat of leading edge of aircraft\'s wing. Vivaldi radiator has been chosen as broadband radiator. The radiator consists of ground plane and metal screen with three-layer printed circuit board placed inside. BSP has been calculated using FDTD method. The number of radiators has been limited by 8 and array step has been taken equal to 0,17. Scattering control of L-band AESA equipped with frequency selective structures (FSS) is discussed, which provides spatial band-stop features to the antenna. During the first phase, double layered FSS (for 8-18 GHz) and double resonances FSS (for 8-12 GHz and 16-18 GHz) has been designed basing on square ring elements. The cases of double layered FSS placement on plane dielectric diaphragm and double resonances FSS placement on curved radome are considered. The radiator of AESA has been optimized con-junctively with all presented FSSs to account mutual influence. During the second phase, the effect of double layered FSS and double re-sonances FSS on the back-scattering diagram and Bragg lobes has been investigated. Double layered FSS placement on plane dielectric diaphragm has provided 2,5-10 times wideband back-scattering reduction in 8-18 GHz frequency band. Double resonance FSS place-ment on curved radome has provided 1,5-10 times Bragg lobes reduction in 8-12 GHz and 16-18 GHz frequency bands. Also, FSS blindness caused by resonance in a volume between FSS and ground plane for the some Bragg lobes has been discovered.

 

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